Players can certainly hear fans.  I've had players on the opposing bench (near
side from my seats) personally respond to me, and players from my own team have
 told me that they can hear me from their bench (on the opposite side of the ar
ena).  If they can hear onr person screaming alone (though admittedly quite
loudly :-) then they can definitely hear many fans chanting in unison, or a ban
d playing.
                                                      Carl